Study Of Surfactant Effect On Motion Characteristic Of Bubbles

In flotation,air is normally introduced into flotation system in the form of small bubbles,as the carrier,to bring the purpose mineral which stick on bubbles to the liquid level.The size and movement characteristics of the air bubbles will directly affect its ability to carry mineral.Surfactants are often used to adjust the size and stability of the bubbles.Therefore,studying the motion characteristics of bubble under the action of surfactant is a guidance to improve the flotation efficiency.In this thesis,we select polyoxyethylene octyl phenol ether?OP-10?and methyl isobutyl carbinol?MIBC?two kinds of surfactant,and study motion law of a single bubble in OP-10 solution and MIBC solution.First of all,we use Kruss K100 surface tension meter to measure the surface tension of surfactant solution of different concentrations and then take the single bubble motion in the solution by OLYMPUS i-SPEED3 High speed dynamic camera system.Finally extract the bubble motion characteristic parameters using i-SPEED Suite and Image-Pro Plus7.0 software,including air bubble size,shape,trajectory,coordinates,the rising velocity and so on.Study the bubble dynamics properties based on the extracting experimental data.It is concluded that the influence law of the surfactant obtained on the bubble size,shape,locus,velocity and coefficient of drag force.The research results show that the bubbles generate and break away from needles first do accelerated motion,do deceleration speed after reaching the maximum velocity,finally do stable movement near a speed flutuation.With the increase of dosage of surface active agent,bubble trajectories gradually become a straight line from zigzag.Bubble diameter,bubble velocity and bubble deformation are decreased with the increase of dosage of surface active agent.Using the classic bubble velocity model and the drag force calculation model respectively predict the velocity and drag coefficient of the bubbles and found that error is larger with the experimental results.We conducted nonliear fitting using experiment data based on the velocity of the Stokes classic model and the S-N drag coefficient calculation formula,and get corrected velocity prediction formula and drag coefficient calculation formula.For the correction formula of the velocity,the maximum error is 8.93% and the mean absolute error is 5.675%.For the correction formula of drag coefficient,the maximum error is 1.5% and the mean absolute error is less than 1%.Through the comparision of the data of previous studies,found that the drag coefficient model can predict the drag coefficient accurately in the Reynolds number?Re=8-30000?,the number of Eo?Eo = 10-2-103?and the number of Mo(Mo =10-¹⁴-10⁷).